Airplane heating system



Aug. 29,1944. 5. E. HEYMANN AIRPLANE I IEATING SYSTEM Filed April 2;.1945

v film/5% conditions of operation Patented Aug. 29, 1944 UNITED STATES PATENT OFFICE,

AIRPLANE HEATING SYSTEM Seymour E. Heymann, Chicago, Ill;, assignor to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia Application April 2, 1943, Serial No. 481,552 a Claims. (0L 29.7-12.3)

My invention relates to airplane heating systems and has for its object the connectiontoi a plurality of internal combustion heaters distributed in different compartments of an airplane with a plurality of airplane engine fuel feeding systems in such a manner that under ordinary amounts of fuel and air mixture will be taken from each. engine and substantially equal amounts of the products of combustion from the internal combustion heaters will be delivered into the intakes of each of the engines.

The object of the invention is to distribute the load of the plurality of heaters between a plurality oi engines so long as the engines are functioning normally, but to operate all of the heaters from. one engine in the event the other one or more engines of the plane go out oifoperation. More particularly the object of my invention is to provide a system in which a mixture of fuel and air suitable for combustion in internal combustion heaters is derived from the high pres-' sure sideof the superchargers of two engines, from which the mixture of fuel and air flows in parallel to the'intakes of a plurality of heaters,

and-in which the discharge from a part of the heaters is returned to the intake side of one supercharger and the discharge from the remainder of the heaters-is returned to the intake side of the other supercharger.

. Another object of my invention is to provide a" heating system in which each engine of an airsubstantially equal through the conduit into the inoperative supercharger.

The accompanying drawing is a diagrammatic illustration of my invention as applied to an airplane having two motors and four superchargers. I

In the diagrammatic illustration three internal combustion heaters are illustrated, the heater I being of substantially twice the size of each of the heaters 2 and 3. These heaters are of the well known type in which a combustion chamber is conductively associated with a chamber through which air is passed to be heated, the combustion chambersbeing sealed except for its intake and discharge openings, so that no products of combustion can come into contact with the airto be heated which passes through the plane has two superchargers, one power driven by the engine and the other driven by ,the exhaust gases from the engine, and "in which the air is carbureted prior't'o its admission into the power driven superchargers and in which carbureted fuel for the internal combustion heaters is taken in parallel from the high pressure sides of the power driven superchargers and in which the products of combustion are delivered from a' .part of the internal combustion heaters to the low pressure side of. one of the power driven superchargers and the products of combustion from another part of the internal combustion heaters perchargers goes out of use because its enginehas been disabled one or the other of the check valves will prevent the flow of mixture backward 4 .is delivered to the low pressure side of the other of-the power driven superchargers. In carrying out my invention I provide a check heater. l

The airplane on which my heaters are mounted is diagrammatically illustrated in dotted lines.

Two nacelles 5 and 6 are illustrated as the housings for engines having superchargers 'l and 8 which are power driven from the engines and superchargers 9 and ill which are driven by the exhaust gases from the engines.

Extending out of the high pressure chambers of superchargers i and 8 are the conduits i2 and I3 communicating with a conduit l4 through check valves l5 and 16. The check valve I5 permits a flow of combustible fuel mixture from conduit l2 toward conduit H but prevents a reversal of flow. The check valve it permits a flow of combustible mixture from conduit l3 to conduit H but prevents a reversal of flow. The conduit l4- leads'into a distributor H from which conduits l8, l9 and lead respectively to the heaters I, 2 and 3. 'Each of the conduits I8, is and 20 is provided with a solenoid valve 22,

these valves being individually controlled by electric circuits, not shown, for cutting off and on the respective heaters in accordance with the temperature requirements of the cabins in which the heaters are located. t

The exhaust pipe/ from heater i connects to the intake of supercharger I at a point posterior f to the discharge from supercharger 9. The ex haust pipes 26 and 21 from heaters-2 and 3 discharge into a common pipe 28 which connects with the intake of supercharger 8 at a point posterior to the discharge of supercharger l0.

Turbo-carburetors 29 and 30 are preferably included in the conduits extending between the high pressure side of supercharger 9 and the low pressure side of the supercharger I, and the high pressure side of the supercharger l0 and the low pressure side of the supercharger 8, re-

spectively, although it is to be understood that these carburetors may be located anterior to the I intakes of superchargers 9 and I0, if desired.

The advantage of utilizing two superchargers in series, one of which is power driven and the other of which is driven from exhaust gases, is that the eil'ectivenessof the exhaust gas driven superchargers increases with the rarefication of the atmosphere because the pressure differential between the exhaust gases as they leave the engines and as they emerge into the atmosphere increases with the rarefication of the atmosphere. This'results in a comparatively uniform pressure being maintained in the conduit between the two superchargers at the points where the exhausts from the heaters enter the supercharger conduits.

In operation, assuming that both of the engines are functioning normally, carbureted air will pass from the high pressure sides of each of the superchargers i and 8, through conduits, l2 and i3, past check valves i5 and to into the common conduit to, thence through distributor ii to conduits l8, l9 and 20, thence through the solenoid valves 22 into the combustion chambers of the internal combustion heaters i, 2 and 3. The internal combustion heater I being of substantially twice the size of either of the heaters 2 and 3,

the flow through conduits I8 is substantially the 7 same as the combined flow through conduits i9 and 20. The exhaust conduit 25, leading from internal combustion heater l, conducts substantially the same amount of burnt gases into the intake of supercharger 7 as is conducted by exhaust pipe 28 into the intake of supercharger 8.

If one of the engines goes out of commission and stops, the pressure in the conduit I2 or i3,

as the case may be, will drop to that of atmosphere at the height at which the plane is flying. The pressure in the other of the conduits H2 or 53 associated with the supercharger of the engine which is still operating will be called upon to deliver a larger amountof carbureted air than it was called upon to deliver when both engines were operating, but the flow through the distrlbutor ii will remain substantially constant because the pressure upon the exhaust pipe at the point where it enters the conduit between the now stationary superchargers will have dropped to that of atmosphere, thus creating a tendency to a greater flow of combustible mixture through the internal combustion heater or heaters from which the exhaust to the disabled engine extends. A somewhat balanced condition is therefore created which permits all of the heaters to continue their operation, although the one having its exhaust pipe connected with the engine which is still in operation will receive slightly less combustible mixture than before, whereas the heater or heaters connected with the superchargers of the engine which has stopped will receive the same or perhaps slightly more combustible mixture than before.

The effectiveness of the heaters are substantially the same at low altitudes as at high altitudes, since the intake and discharge pressures from the power driven superchargers I and 8 remain substantially the same thoughout altitude changes. In fact, the superchargers 9 and II) have so slight pressure producing effect at low altitudes that there is substantially no difl'erence in the discharge pressure of the heaters at low altitude, depending on whether or not the engine to which the exhaust from the heaters extends is in or out of operation. Since the discharge of the heaters in operation without increasing the delivery of products of combustion to one of the engines when the other engine is out of operation..

'While I have described my invention as applied to a diagrammatic illustration, it will be readily understood by those skilled in the art that structural variations of the diagrammatically illustrated parts may be made without departing from the basic features of my invention. I therefore do not wish to be limited to any particular structural details nor to the precise connection of the elements as herein diagrammatically illustrated, but wish to include within the scope of my invention all modifications and variations which will readily suggest themselves.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent of the United States is:

i. In an airplane heating system two engines each having a pair of superchargers serially connected, one of each pair being power driven by its associated engine and one of each pair being propelled from the exhaust of its associated engine, two internal combustion heaters, a conduit connecting the high pressure chambers of said power driven superchargers with each other and with the intakes of said internal combustion heaters, an exhaust pipe connecting thedischarge from one of said heaters to the intake of one of said power driven superchargers, and an exhaust pipe connecting the discharge of the other of said internal combustion heaters to the intake of the other of said power driven superchargers, the connections of said exhaust pipes to the supercharger intakes being between the the exhaust driven superchargers and the power driven superchargers. I

2. In an airplane heating system two engines each having a pair of superchargers serially connected to provide two stagesiof compression, a

carburetor in the conduit between said super-' chargers, two internal combustion heaters, a conduit connecting the high pressure chambers of the second stage superchargers with each other and with the intakes of said internal combustion heaters, an exhaust pipe connecting the discharge from one of saidheaters to the intake of one of the second stage superchargers, and an exhaust pipe connecting thedischarge of the other of said internal combustion heaters to the intake of the other of said second stage superchargers, the connections of said exhaust pipes to the supercharger intakes being between the carburetors and the intakes of the second stage superchargers.

3. In an airplane heating system two engines each having a pair of superchargers serially connected, one of each pair being power driven by its associated engine and one of each pair being propelled from the exhaust of its associated engine, a conduit connecting together the high pressure chambers of the two power driven superchargers, a pair of check valves in said conduit, one permitting the flow of combustible mixture from one supercharger into-the conduit and the other permitting the flow oi combustible mixture from the other supercharger into the conduit, a pair of internal combustion heaters, branch lines connecting with the said conduit between said check valves and extending-respectively to the combustion heaters to the intake oi the other of intakes of said internal combustion heaters, exhaust pipes extending from said internal com-' bustion heaters respectively to the intakes of said power driven superchargers, whereby the combustible mixture is normally supplied to said internal combustion heaters in parallel from said power driven superchargers in parallel, each check valve serving to prevent the flow of combustible mixture from the conduit to its associated supercharger when that supercharger ceasesto operate. i

4. In an airplane heating system two engines, each having a supercharger for delivering combustible mixture to the engines, three internal combustion heaters, one heater being of a capacity substantially equal to the other two heaters, a conduit for connecting the high pressure chambers of said superchargers with each other and with the intakes of all of said internal combustion heaters, an exhaustpipe connecting the discharge from the large heater to the intake of one of said superchargers, and an exhaust Pipe connecting the discharges oi the two smaller internal v exhaust pipe to the supercharger intakes being said superchargers;

5. In an' airplane heating system two engines. each having a'pair of superchargers serially connected, one supercharger of each pair being power driven by its engine, the other-supercharger of each pair being driven by the exhaust gas from its associated engine, three internal combustion heaters, a conduit connecting the high pressure chambers of the power driven superchargers with each other and with the intakes of all of said internal combustion heaters, an exhaust pipe connecting the discharge from one of said heaters to the intake of one of said power driven superchargers, an exhaust pipe connecting the discharges of the other two internal combustion heaters to the intake oi the other of said power drivensuperchargers, a carburetor for supplying a combustible mixture to the intakes of said powerv driven superchargers, the connections of said between the carburetors and theintakes o! the power driven superchargers.

SEYMOUR E. 

